How to use mysql union to realize full external join query

In this article, the editor introduces in detail "how to use mysql union to achieve full external join query", the content is detailed, the steps are clear, and the details are handled properly. I hope this "how to use mysql union to achieve full external join query" article can help you solve your doubts.

1. Union is not a way of multi-table join query, which combines the query results of multiple query sentences into one result and removes duplicate data.

2. The full outer join queries the data of the left and right tables, and then connects according to the connection conditions.

Example

# read here with BSELECT * FROM t_category c LEFT OUTER JOIN t_product p ON c.cid = p.cnounionSELECT * FROM t_category c RIGHT OUTER JOIN t_product p ON c.cid = p.cno of A union on the left. This article "how to use mysql union to implement full external join query" has been introduced. If you want to master the knowledge points of this article, you still need to practice and use it before you can understand it. If you want to know more about related articles, Welcome to the industry information channel.